Synthesis and characterization of brominated naphthalenes representative of the naphthalene contaminants of the fire retardant chemicals PBBs continues. These include pentabromomethylnaphthalene, 14-labeled 1,2,4,6,7-pentabromonaphthalene and work toward modification of the 1,2,4,6,7-pentabromonaphthalene as a haptenic compound in radioimmunoassay work.